으면 미치다

if X, you'd go crazy

A conditional "-(으)면" plus 미치다 "go crazy". The literal use is here: I feel like I'd go crazy without it, hearing that would drive me out of my mind, being stuck indoors is making me lose it. But the past form 미쳤다 after a conditional is slang for "that would be incredible", not madness — if you could actually buy Japanese companies with this, that'd be insane; if you could build it that high, amazing. Roughly half these lines are that admiring second use, so the tense on 미치다 is what to check.

Register: casual